Bring 4 cups water and 1 teaspoon salt to a boil in a medium, heavy saucepan; gradually whisk in grits. Reduce heat; simmer, uncovered, 20 to 25 minutes or until thick, stirring often. Remove from heat, and add 1/4 cup butter and Parmesan cheese, stirring until cheese melts; cover and keep warm.
Heat 1 tablespoon oil in a sauté pan or large skillet over medium-high heat; add lima beans, onion, celery, and carrot; sauté 2 minutes. Add 1/2 cup water; cover, reduce heat, and simmer 15 minutes. Add corn; cook, uncovered, 3 to 5 minutes. Remove vegetables from pan; keep warm.
Add remaining 1 tablespoon oil to pan, and heat; add shrimp, and cook 1 to 2 minutes on each side. Add ham and shallot; cook 2 minutes. Add white wine, and cook to deglaze pan (stirring to loosen particles from bottom of skillet). Add lima bean mixture and tomato halves to pan. Cook 1 to 2 minutes or until heated through. Stir in remaining 1/4 cup butter, lemon juice, and Tabasco sauce; season to taste with salt (about 1/4 teaspoon) and white pepper. Serve shrimp and succotash over hot grits.